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If a plane had a laser/infrared ruler its four extremities pointing downward, could that work as an altimeter device?
Laser noob here. I don't know what the maximum range on a high powered laser is, nor a low-powered laser for that matter. Just wondering if this is at all possible. I mention four extremities because it would a combination of the four different laser readings of height. I guess it could be most useful over water, but things could get complicated if flying over rough regions with mountains and valleys, but could be helpful if use in conjunction with a map.

It could work, but what problem would it solve?  There is nothing wrong with the current radio and pressure altimeters.  Lasers would also not work in a lot of conditions where other systems would so why?

First off, it would look cool. Maybe it's a less-expensive option for some types of planes. If we all kept the saying "If it ain't broke, don't fix it." , scientific breakthroughs would be few and far between.

I agree, but a laser system would be worse, so why break something that's working?

Laser systems are better when you want more precision; they're not worse in all cases.

I never mentioned 'breaking' anything. This is an idea, a thought, and questions pertaining to these ideas.

Yes, you could create an altimeter using a laser.  And they exist; See Laser altimetry for aircraft and UAVs by Renishaw as one example.
Laser altimeters, however, have a significant disadvantage over radar altimeters: They can be obscured by weather, like clouds and rain.


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Do stunt jets use laser distance meters to align with one another to maintain formations?
My question is about Jets/planes performing acrobatic formations to stay well-aligned with the other jets/planes in formation. I could see a laser-distance meter coming in handy.

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Can an airplane lift off the ground when lift is equal to weight?
Can a plane lift off the ground at the point when there is the same amount of lift as weight? Or does lift have to be greater?

see: http://aviation.stackexchange.com/questions/13870

Yes they can, in fact aircraft regularly lift off the ground when lift is less than weight. They achieve this by rotating the nose, which provides a vertical component of the thrust vector. See the excellent answers to  this question for a detailed explanation.

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Is a subsonic scram-jet reasonable?
By placing a de laval nozzle at the inlet, can the resulting supersonic airflow allow a scram jet to operate efficiently?

Welcome to Aviation.SE. what do you define as efficiently? some amount of inefficiency cannot be avoided.

First let's clear up some things:

A SCRAM jet is a Supersonic Combustion RAm Jet, where the flow speed in the combustion area is still supersonic. Efficient combustion needs low speeds, hence a supersonic combustion is not a good solution to maximize efficiency. It needs rapidly mixing and burning fuels like hydrogen, lest most of the thermal energy release happens when the gasses have left the engine.
The operating principle of all aircraft engines with continuous combustion is that the kinetic energy of the flow is converted into potential energy, namely pressure. This pressure is needed to convince the hot combustion products to leave the engine at the rear end, where the pressure drops as the flow is accelerated again. If the engine flies at subsonic speed, the first area where supersonic flow is possible is in the convergent-divergent nozzle. Normally, pressure recovery is too small at subsonic speed, and either some turbo machinery or an oscillating pressure wave is needed to increase compression.

A de Laval nozzle (first developed by Ernst Körting in 1878) is a fixed convergent-divergent nozzle and needs high inlet pressure to function. Placing it at the subsonic inlet would require a near vacuum at the outlet to make it work. Using it in combination with a Ram jet would result in separated, subsonic flow with little pressure recovery in the combustion area, and very little thrust could be produced. In principle such an engine would run, but I doubt that it will even produce enough thrust to result in a net thrust gain. Efficiency would most likely be negative.


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Rotax 912 ULS operates well on ground but poorly in air
I have a Rotax 912 ULS in a pusher configuration.
On the ground, run-up is good, the carburetors are balanced, both sides EGT are almost exactly the same, and there is no fouling on any plug.
However, immediately upon takeoff the engine starts running rough. I can see that the EGT on one side drops quite a bit. It feels like it's not running on all cylinders. Upon landing, the issue goes away.
I get the sense that there's some kind of issue which is being caused by the air pressure of being at a fast flying speed rather than a ground speed. The two things that come to mind are carburetors or possibly plug wires.  I've balanced the carbs, checked all the plugs, and done numerous ground run-ups. I suppose I could tighten all the plug wires into the boots. I'm running out of ideas.
The engine runs great on the ground. FYI, this is at a sea level airport with 22C weather. I'm staying in the pattern so I haven't gotten above 1000'.
Any ideas where to look?

What happens if you test your mags/lanes while it’s running poorly?

How is the air intake configured?  How fast do you fly?

That was my first thought too.  If airspeed is the variable it seems that disrupted flow might be in play...

To answer questions above: (1) mags test fine on ground, I'm not brave enough to test in the air!, (2) Air intake is via K&N filters which always have been good, (3) airspeed does seem to be a factor, but why I'm not sure.

forward facing K&N filters.

Is there any baffling or inlet that channels air to the filters?  Because if the filter element is forward facing maybe it's getting too much ram air and you need a supersonic intake ramp to slow it down?!  Conversely if the end of the filter faces forward and the element draws from the side, perhaps the intake flow gets turbulent at higher speed and chokes the engine?

Yes there are baffles. To be honest it has worked well before.

Air intake to fuel tank open enough?

"it has worked well before." Before what?  I.e. have you made any changes since the time it was running good?

In the winter. It sat for 6 months. I’ve replaced the fuel but I just discovered that the maximum octane in Canada is 94 not 91 as I thought. The station I bought fuel from only had 91 so I thought that was the max. I’m draining right now and trying with 94.

The answer appears to be (mostly) spark related, not air related as I originally thought.
After replacing one carb diaphragm and cleaning the light aluminum corrosion on that carb, I saw no change. Balancing the carbs showed no change. Carb floats were good although the bowls showed some residue from fuel which had evaporated; I cleaned this too. The rubber parts used to mount the carbs were also in good shape with no tears or cracks.
So that left spark. I noticed that my previous mechanic had used Denso IXU24 5309 iridium plugs which are not specified by Rotax. So I went to the auto parts store and got NGK DCPR8E 4339 plugs as specified (originally!) by Rotax. A quick change and that 99.99% solved the roughness problem.
Perhaps I'm focusing too much on it but that last 0.01% is the occasional - like once every few minutes - incredibly light feeling of roughness for about 1/10 of a second in flight. I'm going to chalk that up to being too hyper-sensitive to the engine for now unless there's something else I'm missing.

Thanks for posting the follow-up; this info may be useful for somebody else later with a similar issue.

Any analysis why the roughness only showed up in flight with the spark plug issue? Just curious if anything might explain that bservation.

I think it's possible that the spark plugs were the cause of ground roughness and the aluminum oxidation was the cause of the air roughness. My theory is that the aluminum oxidation created a tiny gap in the "cap" of one carb which had no effect on the ground, but as soon as there was airflow, it pushed the diaphragm down and correspondingly messed up the air/fuel mixture. But because doing that by itself didn't solve anything, I didn't fly it until I changed the plugs so I can't be 100% certain.

The ULS has an issue with their float balls getting fuel inside them. Have you checked your float balls to entire they are in good condition? This should be an uncommon issue but I see still see it quite often still.

If by float balls you mean the carb floats? I did actually replace them a few years ago based on the advisory that Rotax sent out. I suppose it's worth taking a look at them again, will do tomorrow.

One other thought that I had is, could it possibly be a carb diaphragm? It might perform fine on the ground but with air pressure from increased speed while flying (the air filters/intakes are pointed forward) maybe a small fault could cause erratic operation?

Ok so I replaced one of the carb diaphragms because it was in poor condition. The other was fine. I rebalanced the carbs too. Now it runs a lot better but still not perfectly. At least it feels safe to fly. But I still need to get it a bit smoother while flying.

Sorry for the late reply. Glad you got it to run better. What issues are you running into now?

I'm pretty sure the issue has to be spark plugs. My mechanic had been using Denso IXU24 5309 plugs but doing some research I've found that the correct plugs are NGK DCPR8E which is what Rotax shipped it with. I just ordered a set from the auto parts store and I'm going to give it a try.

How’s it running?

Still not perfectly. I am currently investigating whether I should change the setting of the carb pins. It was relocated from a high density altitude environment to a low density altitude environment. The Bing carbs have four positions on the pins, I haven't removed mine to check where they are. What makes me think of this is that the mag drop is 600 rpm on both mags during run-up which seems excessive. Thoughts?

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Garmin 695/696 joystick removal
I have a Garmin 696 with a faulty joystick. I have a parts unit that I'd like to swap the joystick with, however upon disassembling the units, I can see how to disconnect the signal lines from the joystick but not how to remove the joystick itself.

Removing the four screws surrounding it does not loosen it and I believe that the three nuts on top are to seal the joystick itself so I haven't touched those. The entire assembly has a little play to the left and right so it's probably not screwed in. But how it's attached is a bit of a mystery to me.
Does anyone know how to do this? Google has not produced any useful results.

Can you remove the PCB and look on the other side?

I can't. The joystick prevents removal of the PCB.

I find it difficult to see how this fits into aviation as defined in the help centre. On a purely practical basis you might find you get better answers on [electronics.se]

@Hawkman Did you remove the knob on the front side? In such a case, can you post a picture on the front? There's probably some mechanical movement to do to detach it

I did yes. The knob popped right off and there is nothing behind it to unscrew.
It’s an aviation GPS. I assumed possibly incorrectly that more aviation people would be familiar with it. No non-aviation GPS has this joystick.

Maybe those three nuts will take off the black cover for the joystick and then you could have more access? Also what do you mean the joystick prevents the removal of the PCB?

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How to handle vacuum and turn coordinator failure in IMC?
I just earned my FAA instrument rating and a considerable amount of time was spent training partial panel. This meant flying with no vacuum gyro instruments - attitude indicator and directional gyro. After my check ride the examiner said "you fly better without those instruments" which I considered a nice compliment to both myself and my instructor.
In reflecting upon this, I started thinking, what if I had an additional failure of something - how would I handle it? I launched X-Plane and set up an LNAV+V GPS approach on a windy, bumpy low IMC day and gave it a shot. Unsurprisingly, this was HARD.
I used the instruments as follows:

Altimeter / VSI and on the final approach the VNAV glide slope for altitude control. Not too bad.
GPS track and a bit of magnetic compass checking, along with the CDI needle. This is a very poor way to navigate. The magnetic compass obviously has lagging/leading errors and the GPS track is what I'd call a rate instrument - it lags a little.

The main problems I faced were that you can't time turns with no turn coordinator and the bumpy/windy air made constant corrections required. There appears to be no way to identify wings level. You can tell when you're no longer turning but you might be starting a turn the other way.
My strategy as I worked through this was to slow the plane (C172) down with 10 degrees of flaps throughout the procedure to make heading changes have the least effect. In the end, I tried to keep the track as close to the DTK and the CDI as centered as possible - effectively chasing two needles. This resulted in a sinusoidal course when I looked back at it on the X-Plane instructor console.
(By the way, I did land the plane safely but I'm not sure I'd be able to do this in the real world - the workload I experienced in my comfy chair was EXTREME.)
I know the scenario is unlikely but it's certainly possible. There appears to be no guidance that I can find on the Internet about it.
My question: is there a better way to do this? If so, what's the procedure?

"is there a better way to do this?" You mean besides contacting ATC and declaring an emergency because you have lost a bunch of flight-critical instruments?

@MichaelKjörling, well, if the ATC does not have a precision approach radar, they won't be able to help you all that much. And most don't.

The owner of XPlane made an iPad app which you can use as a "standby" AI in real flying. I've lost the link to the article, but the GIST is it is accurate enough to bring you back safely.

Good points above. I hadn't given more thought to the broader picture of this, but let's assume that in my scenario, I'm assuming no precision radar, ATC offers this is the "best" airport and approach for weather and my available fuel. The approach had both vertical and horizontal guidance so that's probably reasonable. As for speed, my thought was that if I was weaving back and forth, I wouldn't go off course too far if I was slow. Again, not too realistic but the maneuvers were what I was interested in here more than the scenario.

In reality, my airplane has a GTN750 with the FlightStream 210. This gives a backup AI on my iPad along with a synthetic turn coordinator so I do actually have this redundancy in the real world. This was more to try out a really tough scenario than anything else. A "bad day in the office" if you will...

I have installed dual Garmin G5s, both with 4 hour battery backup. Both can be used as the AI.  No vacuum system in the plane anymore.  I see more of this occurring in the forum for my plane type, with Garmin and Dynon and others providing Glass instruments to replace vacuum instruments for both Certified and Experimental planes.  Examiners will have to change their approach to partial panel testing.

@JanHudec: Wouldn't an ILS also work?

In hard IMC with no gyros and no turn coordinator, how would you know which way to make control inputs in to start and stop turns?  With no way to identify wings-level, how would you know whether the aircraft was still upright or had rolled inverted?

This isn't exactly your scenario but at my last instrument checkride the DPE asked me how I would descend from VFR-on-top through a solid cloud layer following complete electrical and vacuum failure (in a C172 or something similar). No avionics meant no help from ATC (vectors, or even a PAR approach) and we also assumed that I had no tablet, phone or other external systems that could help me.
The question came at the end of a discussion about aircraft systems and failures and the DPE didn't expect me to have a ready answer because it isn't something you train for. But he suggested this procedure:

Set up the aircraft on an east or west heading to minimize compass turning errors
Use the rudder only to fly a constant heading on the compass; once you have the aircraft going straight, do not move your feet again
Set power and trim for a stable descent at a little above Va and a little less than your usual descent rate, e.g. 300fpm
Sit back, cross your arms and wait to break out. Resist the temptation to touch the ailerons or power.

His reasoning was that by avoiding using the ailerons and power you can avoid going into a graveyard spiral quickly. You may still do it, but you'll do it a lot more gradually and hopefully by that point you'll have broken out anyway. I've never tried it myself, but I'll have to do it sometime with a safety pilot.
In real life, if you can't get to VMC easily then a tablet app with a portable AHRS unit would be a good backup. Although personally, if I ever lost the complete panel my first thought would be to get to VMC, not to shoot an approach. I suspect that for most people, landing in a field is likely to be the much better choice. But like all 'what if' scenarios, it depends.

Now this is an interesting story about the DPE suggesting to use the rudder only (and I am not questioning it a bit). On one of my 135 checkrides an examiner said that he would fail me if he noticed that I 'steer with the rudder only' on a localizer. Aerodynamically it seems using the rudder too much would get you into a spin rather than a spiral. Which, incidentally, is a rather stable way of getting through a layer as long as you are sure there is at least 1000' clear at the bottom (they used to do this in the old days). Spinning a twin though ...

East and west are not the best headings at least for flying at mid-latitudes.  See my answer.

@quietflyer I assume my DPE believed it was best to minimize the turning errors: his point was that you should resist the urge to move the controls anyway. If the compass swings a lot due to turning error then the temptation would be to overcorrect what's actually a minor turn, or turn in completely the wrong direction. Whether or not it works in practice, I don't know (I still haven't tried it!).

@alexsh: Then again, planes back then were a lot easier to get out of a spin (even a fully-developed flat spin) than they are nowadays - lots lighter with lots less angular momentum to null out.

It is possible to use the wet magnetic compass to descend through even a rather thick cloud layer if the air is not too turbulent.  In mid-latitudes in the northern (magnetic) hemisphere it is important to choose a course close to due S-- not further than 45 degrees off and preferably less.  On a southerly heading, the compass will over-react to a slight bank which is extremely helpful.  If your heading wanders to north of magnetic east or west the compass will tend to turn backwards of the appropriate direction for the turn-- this is deadly-- you will likely end up in a steep-banked turn with the compass spinning wildly, reversing direction, etc.
In an aircraft with good yaw (slip)- roll coupling, steer with the rudder pedals rather than the yoke.  This makes the compass over-sensitive to your inputs which tends to prevent over-controlling.
I've seen video of a Cessna 120 descending through several thousand feet of cloud in this manner, with tape covering all gyro instruments.  It was very clear that the pilot was actively making steering inputs, not just relying on the aircraft's inherent stability, which would not have been sufficient to keep the aircraft wings-level indefinitely.
This technique may not work near the magnetic equator to the lack of the "lead" effect-- the over-reaction to a slight bank-- in this area.  Likewise this technique will not work at very high (magnetic) latitudes.
Then there's always the recourse of a hand-held GPS, set to the compass-like "heading" display (actually direction of ground track).  In my experience there's too much lag for this to be reliable, and the wet magnetic compass offers superior guidance.  This not be the case with higher-performance GPS units, especially those that simulate aircraft-style displays.

missing word ( this MAY not be the case) in last sentence

Note that in most aircraft the wet magnetic compass-- or alternatively a vertical card compass which still suffers from many of the same errors --- is mounted in such a location that it is almost impossible to practice flying "under the hood" by reference  to this device.  This may partly account for the diversity of opinions on this topic.


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How does a pilot know if he has headwind, tailwind or crosswind?
While in cruise, without GPS how does a pilot know the wind direction? The airspeed sensors only register forward speed. Is it a matter of reaching waypoints sooner or later? And if flying on a compass heading how do they know what their ground track is and whether or not they're being blown off course? Especially with no visual reference.

If you can see the ground, there's a simple way to tell if you are in a crosswind. You can see where you're going, because you are going toward the objects on the ground that are coming toward you. If those objects are off to one side, you're in a crosswind.

With no visual or instrument references you don't know if you have a headwind, tailwind, or crosswind.
You also don't particularly care because you're flying a plane with no way to navigate and therefore have more imperative concerns.

With visual references it's something you can determine with a little thinking and some intentional oversimplification:

Headwinds mean your ground speed is lower than your airspeed.
If your airspeed is 100 miles per hour and you're flying a 25 mile leg it should take you 15 minutes. If it takes you 18 minutes you know you've got a headwind.
Tailwnds mean your gound speed is higher than your airspeed.
If you're flying the same 25 mile leg at 100 miles per hour and it only takes you 12 minutes you have a tailwind.
Crosswinds are a bit more difficult: The easiest way to tell you have a crosswind is if you know what your magnetic heading should be in order to fly toward a given point and you have to point the nose at a different compass heading in order to maintain the desired ground track you have a crosswind.

Note that you almost never have a direct headwind, tailwind, or crosswind, but rather some wind at an angle to your direction of travel which will have both a crosswind component and a headwind/tailwind component. The wind speed and direction can be computed using an E6B flight computer with relatively little effort.

If you have instrument references the problem gets easier:

GPS is the ultimate solution -- it can display your ground speed and ground track, from which you can derive the winds. GPS systems that know your airspeed can even calculate the winds for you so you don't need the E6B anymore (unless the GPS breaks).
VORs provide a magnetic heading reference, which simplifies the crosswind calculation (and largely eliminates the need to do one to figure out your crosswind correction angle: Just keep the needle centered and you have your desired crosswind correction).
It doesn't give you the wind speed and direction without some additional data (how long it takes you to cross some waypoint or fix), because you still need that information in order to determine how much of the wind speed is acting as a headwind, tailwind, or crosswind component.
DME systems can give you your groundspeed. In combination with the VOR this gives you the same information as the GPS and makes determining the wind speed pretty simple.
ADFs can be used for this kind of calculation in the same way as you would for a visual waypoint: If you expect to be flying due north to head toward an ADF beacon and you're flying 010 degrees to keep the pointer needle where you want it then you know you're dealing with some crosswind component.

Pre GPS how did flights navigate over the ocean? I'm assuming VOR/DME are line of sight. How far away can you read them?

@TomMcW We covered that over on this question - it can range from "Take an educated guess at the winds, then point the nose "that-a-way" and fly until you hit land!" (like this guy) to celestial navigation on older airliners, up to complex inertial reference systems and LORAN-C on pre-GPS modern aircraft.

I guess that's why so many people have gotten lost over the ocean. I was surprised to read somewhere on the board that some older airliners came with a built-in sextant.

"if you know what your magnetic heading should be in order to fly toward a given point and you have to point the nose at a different compass heading in order to maintain the desired ground track you have a crosswind." Even if you don't know your magnetic heading, if your plane is tracking in a different direction from the one it's facing, you have a crosswind. :)

In addition to the other answer (which is great) some of this planning happens before the flight leaves the ground. In the flight planning process you can get both winds aloft and winds at various airports in your route via the ATIS. While it is true that winds will change over time (if you are on a long flight) headings are pre calculated with the known winds at the time of departure. If you are planning a very long flight you can check the outlook forecasts (which may not end up being accurate) and plan your headings with those.
Once in the air you can listen to the ATIS along your routes to get live winds below you. This is of course assuming you know which airport is beneath (or near) you at a given time. You may also be able to get weather from a Flight Service Station in route or Flight Following if its provided. Again this is reliant on you knowing where you are, aside from flight following which will actually tell you where you are if its provided.
This all assumes you have a functioning 2 way radio.


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I want to get as much information i can get to start a new airline who can help me please?
I have been researching about the aviation industry and i have some questions about the leasing and buying procedures and faa ,fcc permissions costs, i would really appreciate your help , thank you

Cost: More money than you have if you can't afford actual paid consultants.

What is the actual question here? It is great that you have some but this isn't one.

If you were planning your own airline startup, the first thing you would need to ask and answer is "What is my target market"? To answer this question well, you have to look at what the existing aviation industry does, and does not, already provide. Your initial competitive advantage against much larger competitors with economies of scale is going to be the ability to do something that they aren't doing now, and that advantage will be sustainable, thus keeping you in the game longer, if the existing airlines can't or won't do what you will.
The last big U.S. airline startup to remain successful today, JetBlue, was in 2000, and was started by former Southwest employees and execs to create a similar airline with a few more frills up in the Eastern Seaboard. It took hold after a dramatic decrease in competition in the region following 9/11 and the major airline mergers (Northwest with Delta, Continental with United, TWA with American) and the collapse or absorption of several smaller discount lines like Midwest, America West etc. leaving a vacuum at several major airports in the East that the largest surviving discount carrier, Southwest, didn't (at the time) have the fleet size, regulatory approval or low-cost gate rental arrangements to fill.
To start a successful airline, you first have to identify an opportunity like that. That requires in-depth market analysis; how many airlines serve each airport? Where can you go? At what prices? How about nonstops? The information about what flights are available where and at what cost and what amount of rigamarole (stops, layovers) is public and widely available through any travel site. The number of passengers on each flight, and the complete itinerary of each passenger including their ultimate destination, tends to be pretty jealously guarded by airlines to prevent just this kind of data mining by potential competitors.
Having analyzed where people want to go, how they currently get there and at what prices, you might find an opportunity. People in Lubbock and Waco, Texas, for instance, pretty much depend on regional service to Dallas to connect to a larger flight practically anywhere else. You might identify that people in Waco commonly want to get to St. Louis (for whatever reason) but the only available flights are through either Dallas or Houston, nothing direct. If you can offer a nonstop flight at a similar price (or even beat the layover flights) you have yourself a business opportunity. You'll look across the entire map to find more of these, and put together a set of routes that you're confident you could operate profitably. To determine profitability, you'd need to know both the direct and indirect costs of running the route. Fuel, pilot and flight attendant time are your primary direct costs; everything else, from the cost of the aircraft itself, gate rentals, gate staff, ticketing counters and staff, company ground staff, scheduling and administrative staff, corporate floor space, and your own salary is all overhead. You have to reliably estimate all this to determine the allocated cost of running the route, to determine the breakeven ticket price of an 80% full plane, to see whether that price would compete with the airlines currently serving that airport on a similar route.
Using these identified potentially profitable opportunities, you craft a business plan; you'll offer direct service on narrow-body jets, between 50-100 people per flight, between these various under-served cities. These facts will help you determine your basic business needs. First, you need an "Air Operator Certificate". This is actually one of the last things you actually receive, once you have at least one plane and a plan to fly it for hire along at least one route, with arrangements for ground support in place at your destinations. To get all those things, you need money. So, you take your business plan, including the plans to purchase the aircraft you'll want to run the routes, and take that to banks and potential investors. Depending on the economy at the time, there's typically a lot of startup investment capital available, however the airline industry has been perceived as extremely risky for at least a decade now, so venture capitalists will be extremely skittish about fronting the millions of dollars needed to buy or even lease a few Bombardiers or Embraers.
Assuming you can pull together the capital you need, you set the plan in motion. You start recruiting pilots with the proper certifications (your flight crewmen will need ATPLs to fly a plane being operated as part of a "commercial airline"; a jet taxi/timeshare business like NetJets can get away with ordinary commercial-level pilots because the business is structured and operated differently), you start hiring ground support and administrative staff, you sign on the dotted line for the plane deliveries, you start making arrangements for bulk fuel purchases at your airports. Eventually all the pieces will fall in to place, your new airline will be issued its AOC and you'll watch your first flight depart the gate with ticketed passengers aboard.
Then the analysis continues; were your estimates correct? Was there demand for your new nonstop route? Did the price you set and the number of customers you got cover the cost of the flight itself and all the other services you needed to get the passengers onto it? If so, pat yourself on the back and continue flying. If not (much more likely), identify what's off. Are you not getting the fuel price you thought because you're small potatoes for the airport's fueling cartel? Did not enough passengers book? Are the pilots or ground crew costing you more than you thought? Can you take these new numbers into account and increase your ticket prices to cover them, or is the problem that you flew a half-empty plane and need to attract more customers to get the per-trip revenues up to your estimates?
Or, did you just fly a brand-new plane full of people who paid more than they otherwise would have, on a non-stop no-frills flight on competitively-priced fuel to another airport with minimum support staff, and still lose money? That's what I thought. That's likely because you set up a network of one or two flights a day out of each airport, for which you still needed to rent time at gates and ticketing counters, and adequately man them both visibly and otherwise. You need to identify more routes you can run, even if the gross margins are smaller, because those additional routes with the same ground staff will make the overhead of running any flights to or from that airport less, making the flights profitable because one flight isn't expected to cover the cost of everything there to support it.
If you can't make it work before the investors cut off the funding, then you go bust. You declare Chapter 7, auction off your assets (planes, ground vehicles, gate/counter facility leases) to the highest bidder, and walk away. You won't be the first nor the last airline in history to have done that.
The actual prices charged by airlines to land each plane, rent a gate, etc are public information but vary by airport (and airlines can negotiate on these fees as they represent a lot of business for the airport). The cost of each plane is also easy to find, as are median salaries for various types of transportation workers (as the companies are often public, so are the CBAs between an airline and various unions). This is all just academic number crunching. The hard part is identifying potential flights with enough customer demand to make operating a flight profitable. The usual way airlines have cut in is to compete directly on price, which is part of the reason the airline industry has until very recently been performing so poorly as an investment; upstart discount carriers flying cheaper fleets to cheaper airports in the same cities have completely destroyed the traditional service-oriented business model.

I have already chosen a target market, and currently seeing an opportunity like the one you mentioned earlier which is really the reason i wanted to start this, i come from the Dominican Republic , this country has a lot of air passenger growth thanks to tourism which is rising tremendously and the country doesn't have an airline, the routes that fly here are a few but are extremely concentrated and the market is dominated by 3 American carriers making their services really bad and ridiculous prices. where i need help is projecting startup and operating costs

"The last big airline startup to remain successful today, JetBlue, was in 2000" What, the last in the whole world? Oh, wait. You forgot almost the whole world, unless you're going to claim that, say, Vueling isn't "big" because they only have about half the number of planes that JetBlue has.

OK, that particular stat was U.S.-centric. There isn't another U.S.-based airline to earn its AOC and grow at the rate JetBlue did since JetBlue, and a large majority of U.S. airlines started since then have shuttered. Vueling and Virgin America (which cheated IMO as it's the U.S. spinoff of the already-successful Virgin Atlantic) are the two most notable of a very short list of airlines started after JetBlue that are still viable at all.


text:
Is it possible to communicate an everyday computer with the ARINC bus?
Lately I've been wondering if it's possible to interface an everyday computer with the ARINC buses (either 429 or AFDX).
This would be very useful for simulation, testing and prototyping purposes. For example, we could write a computer program that sends ARINC labels to the bus and see how the avionic systems react to it.
But I think that the greatest challenge would be in the physical layer.
The image on the left shows some connectors that we can typically find in everyday computers. The image on the right shows the connectors that we can find in the front panel of an avionic system.

At first glance making such a connection does not look straightforward.
Nevertheless I've done some research and I have found devices which seem capable of interfacing a computer with the ARINC bus via the USB port:

These pocket-sized USB adapters are the easy and portable way to interface your computer to ARINC 429 and ARINC 717 Avionics
  databuses.
Source: Astronics

So connecting a computer and avionics is possible in theory. Still, I don't see how I would be able to connect this USB-ARINC adapter to the avionics box, since the connectors are different.
So there must likely be an access point somewhere in the avionics where this adapter can be connected.
This is all I could find.
So again,

Is it possible to communicate an everyday computer with the ARINC bus?
If so, what is the access point where we would connect the wire?
Would there be any other challenges I didn't take into account?

It's something that is already done for testing avionics equipment. A very hobbyist solution can be to create an interface with Arduino or any other micro controller.

"the greatest challenge would be in the physical layer": Not at all. Assuming you have a legitimate physical access to AFDX, the standard connector is a Quadrax (seen on the bottom right side of the LRU in your question), and there are Quadrax-RJ45 adapters. However AFDX switches are likely firewalled, so you would have to spoof a MAC accepted by the switches, and then understand the network topology and other host MACs. Some explanation about IMA use of AFDX in this presentation.

Other than building an adapter for the connector on the box you want to talk/listen to (for ARINC 429) there is really not much to do, assuming you have either an ARINC 429 to RS232 (or USB) converter and the associated software.

Is it possible to communicate an everyday computer with the ARINC bus?

Sure. there are appropriate controllers to be plugged in a slot - or even as USB, like the one you found. After all, basic USB is alread way faster than ARINC 429.

If so, what is the access point where we would connect the wire?

Whatever connector the interface card/box offers. More often than not this may require some special-to-type cable. If you're able to handle a soldering iron and/or crimp pliers, building one is a reasonable job. If not, that's where you may ask the interface supplier to take even more money to sell you a fitting one.
On ARINC 664 (ADFX) it's even less an issue, as there are as well equipment using standard plugs.

Would there be any other challenges I didn't take into account?

Software. As always it's the software there the main cost and effort is hidden. While basic drivers are usually included (for ARINC 429) or default (ARINC 664), any layer above will be specific to the task you're intended to handle - and usually not exactly low priced.
For ARINC 664 it depends even more on the task intended. While basic communication runs on standard Ethernet layer, 664 adds a quality of service at layer 2. Something you OS default driver may not support. Ofc, one may (buy and) install a driver that does, still this might bring trouble on the 'regular' networkside. Due this (and to avoide collisions) adding a separate interface card with fiting drivers may be advised.
ARINC 664 opens another can of worms depending on the application intended. Basically it is a virtual implementation of a bunch of ARINC 429 busses over Ethernet. To make applications work some translation layer may be needed.
Bottom line, buying and pluging an interface in/to your PC is the least complicated step here. And everything beyond that needs in depth knowledge of what is intended to be archieved.


text:
Are ham radio contacts allowed from inside an airplane?
This question probably lies in the middle ground between Amateur Radio.SE and Aviation.SE.
I have seen a couple of videos where ham radio contacts are made with people on board a commercial aircraft while in flight. In one of the videos, contact is established trough the 2-meter band (VHF) with a passenger carrying his hand-held transceiver on board the flight, while in the other video, contact is made trough the 20-meter band (HF) with the captain of the airplane using the airplane's radio transceiver.
I am curious about what do regulations say in this regard.
Are ham radio contacts allowed from inside an airplane?

Airlines generally don't allow you to use radio transmitters inside an airplane, that's why "flight mode" exists

@J.Hougaard: IIRC, in at at least some countries that is a restriction by the radio administration, not the aviation safety one. Cellphones on board a high-flying plane have many more cell towers in line-of-sight than cell phones on the ground, and hop between them much faster at a much higher relative speed. The network protocols are not designed for that use case, and thus, a single cell phone in an airliner may end up preventing several users on the ground from connecting to the network. For example, GSM only works up to a relative speed of ~250kph, beyond that, the shift between when the …

… other end expects the signal to be delivered to when it actually arrives becomes too large (the signal is either early or late). The device will thus reserve bandwidth but never be able to use it.

Since you want answers pointing to regulations, please [Edit] to indicate which country's regulations you're interested in.

This question borders on amateur radio regs, too.  Might be better asked on the Amateur Radio stack.

Do you want only commercial flights? For non-commercial, US Civil Air Patrol search and rescue missions often have and use ham radio frequencies to contact ground-based search teams.

Amateur radio regulations in the US don't care if you're in an airplane, but it's polite to add "aeronautical mobile" as a suffix to the call sign on voice, or "/AM" on Morse code.

Two-way radios are just like any other communications device. If the captain says all such devices must be in flight mode at any particular moment during the flight, you are not allowed to use it and could be arrested if you do. Also, if the captain determines that something you are doing with your communications device is interfering with aircraft communications or navigation, he may order the flight crew to confiscate your device until after landing, and you may be subject to criminal charges.

FCC rules do apply to two-way radios in ways that FAA rules do not. For example, an amateur radio operator must specifically have the permission of the captain (also applies to ships) to operate a ham radio on board.

The regulations say that for any flight on an IFR flight plan (which includes all commercial airline flights) the captain (PIC) is responsible for determining if any electronic device will interfere with the airplane's instruments or communication. If the PIC determines that it will not interfere, they can give permission to use the device in flight. Regular VFR (like small airplanes) have no such restrictions on determining interference, but the PIC can still decide if you can use it or not.

In private aircraft, absolutely!
In my 40+ years as an amateur (W0BTU), I have heard and worked many hams in single and dual engine private aircraft. (aeronautical mobiles).

I think the question is about commercial aircraft. Private aircraft are a different story. If you want to do that you install an HF radio.

@JuanJimenez Yes, but I have also worked them on VHF.

That's what all pilots on aircraft with radios do as well. :)

There are several good reasons to prohibit the use of ham radio transmitters on commercial flights. They were largely detailed in a QST magazine article in August 1996 titled “An Aeronautical Antenna Farm” (I remembered that because I worked at the ARRL at the time). Basically the bottom line is that there is too much risk of interference to critical aircraft communication and navigation systems. The article references FAA Advisory Circular 91.21. While this is not a regulation per se it certainly seems like something all commercial carriers would follow.
The current revision (2017) of this circular is here:
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91.21-1D.pdf


text:
What is the purpose of the black paint below the cockpit windows?
Today I saw the following picture of the B747-400 SuperTanker, which shows a black painted region below the cockpit windows.

I have also seen vintage pictures of other aircraft that also had this black painted region.
What is the purpose of the black paint? Is it for decorative purposes?

It reduces glare (specular reflection).
Football players paint black stripes under their eyes for the same reason.

The legend for the paint scheme is excerpted in the inset, upper right. Item #33 "Antiglare areas shall be painted aircraft black."
If you read this technical manual, which is publicly available, it describes in the body of the text the use of anti-glare paint.

Note - you use the term "specular reflection" which relates to the surface texture. The color provides low Lambertian reflectivity. The coating has to have both properties - be matte (for specular) and black (for Lambertian) reflection in order to minimize the glare. Such glare tends to combine with small surface imperfections in the window (from erosion) to lead to haze - which in turn limits the contrast of the view through the window (even if you can't directly "see" the region in front of the window from the pilot's seat).

I was an air force pilot and instructor. I flew the same aircraft in the training role and also operationally. In the training role it had the blacked out nose but operationally it didn't.
When we were training, it was supposedly easier to visually set and hold attitudes when flying towards the sun, less glare and more contrast.
However I never found it to make any difference. Here are two of the aircraft I flew.


text:
How dangerous are small planes?
first time here so bear with me please.
So it looks to me like there are A LOT of small plane crashes.  Pretty much every week a couple of people die in small planes, at least.
Is this due to the planes themselves, to the pilots, to the bad maintenance on the planes?
Main reason I ask, I'd like to learn (maybe, just maybe) how to fly, or at least try a class once, but I'm very afraid of those small planes statistics.  Are there any websites or similar that explain why so many accidents on those and the reasons?
I asked, can't really start learning with a bigger plane with "real engines" :-)

Hi.  Welcome to SE Aviation!  So it looks to me like there are A LOT - where?  Do you have some reference?

The most common cause is pilot error

@airlivenet  on Twitter is my reference. It seems like it's every week, sometimes more than once a week. And it's usually between 2 and 4 people, so small airplane.

So how many fatal car crashes happened in that same week?  Do you hesitate when you get into a car?  Are you very afraid of getting into a car? I'm guessing you are US?  Where there are about 640 deaths on the road per week.  Of course, more miles driven than flown in GA but according to this report, GA flying is only slightly more dangerous than being in a car.  Don't even consider it (you don't when you get into a taxi) so go flying, get your lessons, enjoy it!

Mmm that is a good point about the fatal car accidents :-). Somehow you always feel in control in the car, like you can manage anything.  It's an illusion I know but. But you are right, maybe it's not as dangerous as it seems.  I'm not going to even try until the Florida storms are done for the summer anyway, so I have time to think about it.  Maybe I will. :-) Thanks!!

@Gemma The same is pretty much true when you're flying an airplane. For that matter, with an airplane, I would argue that maybe you're in even more control, since you don't have to worry nearly as much about being killed by someone else doing something stupid. Not that it never happens, but it's much more rare than with cars, since airborne traffic separation is much greater than road vehicle separation.

@reirab that is true :-)

Related question on the perceived danger of small aircraft. And welcome to Aviation.SE

@Simon The report you link gives aviation statistics as events per hundred-thousand hours, and motoring statistics as events per hundred-million miles. Geoff Dalgas has done the conversion, assuming an average driving speed of 50mph: flying in a private plane has around 20x the fatality rate of driving. That factor increases if you assume a lower average speed (which seems likely to me, since a heck of a lot of driving is urban and/or traffic jam). I'd call that significantly more dangerous, though still pretty safe.


text:
Passenger GNSS lock during ascent and descent
When flying on commercial flights for the past several years I've used GNSS on my smartphone to track my location for fun. The signal strength in the cabin isn't ideal, but it's generally good enough to maintain a lock for most of the flight. However, on most flights I will lose my lock shortly after takeoff until we finish our ascent, and again as we begin our descent until shortly after landing. This doesn't happen every time, but often enough that I expect it at this point. And I've noticed it happen with several different smartphones I've owned over the years.
Is there any reason why GNSS signal should be weaker in the ascent and descent stages? Is it harder for it to track significant vertical changes? Is the signal weaker in some of the atmospheric layers we pass through? Does the aircraft itself put out signals that might disrupt my phone's ability to pick up GNSS signals? Or is this just confirmation bias?

In theory yes, the wing, no longer horizontal, may hide satellites low on the horizon. This, added to the fact one half of the sky is already hidden by the fuselage, may prevent to lock on the four satellites required to compute a fix. Most GNSS receivers have a graphic plot showing the azimuth of the satellites in sight, this would be useful to confirm this possibility.

Confirmation bias.
However, the aluminum fuselage does provide shielding from the signal. Your phone should be next to the window. But even then it's only receiving satellite signals from satellites "in view", and just a turn away once the phone has a lock on a particular satellite constellation, may force it to start searching for satellites again and you lose the position signal.
You will generally see GPS systems installed with a dedicated antenna on the roof somewhere so it's above the sheet metal.
My own airplane has a bubble canopy and doesn't need a dedicated antenna, and the built in antenna in my phone works fine for VFR navigating with no sheet metal to shield it.

And, on the ground, the phone can use cell phone towers to get positioning information. That assistance is lost shortly after takeoff.


text:
Are squawk codes used with ADS-B?
When using ADS-B are squawk codes still necessary or does the unit provide a discrete code (like a tail number or something) that is recognized by ATC?

Are you asking if a transponder is still required? The answer to that question is absolutely yes. Having ADS-B out doesn't remove the requirements for certain airspaces where you need a transponder. Sounds redundant but makes sense when you think of all the existing TCAS systems that rely on it.

@RonBeyer I may be wrong about this but I thought the goal in the US was for ADS-B to replace mode c/s in the near future. But the question is more about if the system uses squawk codes.

ADS-B uses a unique code assigned to the airframe for it's life.  Is that what you are asking about?

@Simon Does the atc system use that code to recognize you?

ADS-B does not use squawk codes, and squawk codes are not going away anytime soon, see FAA ADS-B FAQ, #21 - Will Mode-C Transponders be required indefinitely? Its possible in the future that ADS-B will remove the transponder requirement, but not in the near future. So the system will continue to use transponder codes as far as I'm aware. The FAQ page I linked has some good info.

@RonBeyer Reading that very page is what prompted my question. I had misread the sentence that said "not in the near future, though." I was just kinda wondering if you're not in contact with ATC and squawking VFR if ATC can see info like who you are or what type of craft you are

Yeah, ATC should be able to see at least your N-Number and aircraft type if you are squawking VFR, as per Voretaq's answer below. I'm not sure if you should count on it though until NexGen is fully implemented and all radar stations are upgraded.

Yes, squawk codes are still used and required with ADS-B.
It's possible that in the future this may change, but because of the bifurcated implementation the FAA has chosen for ADS-B I don't think it's likely.
ADS-B operates by giving additional information beyond the Mode A (squawk) code - this is either encoded on the 1090MHz transponder frequency (Mode S "Extended Squitter" - what most of the world uses) or sent on a separate frequency (the 987MHz "Universal Access Transceiver" frequency, which is a US/FAA only thing mainly intended for light GA aircraft).
The Mode S and Extended Squitter data includes things like the aircraft's unique Mode S address (a 24-bit number assigned to the aircraft by its national registry, in the US this is linked to the N number), and may also provide the tail number or flight number. The ATC radar system will accept and display this information for the controller.
At the moment the Mode S/ES data is not used as a substitute for the Mode A transponder code, but because Mode S data is coming through the ATC secondary radar system it's all immediately available with the secondary radar return the same way a Mode A squawk code is, and it's possible that the FAA may use the Mode S ID in place of the Mode A squawk code for these aircraft in the future.
The 987MHz UAT transmissions also include the Mode S address (because it's a useful unique identifier for a given aircraft) and flight ID/tail number can be sent as well. Information from UAT transmitters is received through separate ground stations and recombined with the radar return in the ATC radar back-end.
There's some magic to that recombining which is out of my depth, but my limited understanding is that since the UAT data isn't directly correlated with a radar return squawk codes are part of how the two are matched up (the radar computer knows your N number by your discrete squawk code, the UAT ground station knows it from your Mode S ID - if they match and the position data is within reason the ADS-B information can be associated with your radar data block).

The ADS-B data format actually includes a provision for broadcasting the Mode A code, so no fanciful correlation with SSR data is necessary to display it.

@HenningMakholm Do you have a reference for that? I thought there was something for it (it makes sense!) but I couldn't find anything in a quick search, and all the stuff I've been looking at is 1090ES so I'm not too familiar with the details of ADS-B Out on UAT hardware.

What I looked at was DO-260B, which is 1090ES, but I (perhaps wrongly) assumed that it's the same message formats that are being tunneled over the UAT channel. (For 1090ES, the draft of DO-260B that I was able to read without paying through the nose adds the Mode A code to the DF=17, Type=28, Subtype=1 message).

And now I discover that UAT actually uses a completely different message format, so I actually don't know what I thought I knew. :-(


text:
What are CAS and EAS used for?
What are calibrated airspeed (CAS) and equivalent airspeed (EAS) used for? When would a pilot need to know these?

I can't believe this has not been asked/answered on here before, but I couldn't find anything on them.

Equivalent Airspeed is a measure of dynamic pressure, the quantity on which most aerodynamic properties of the aircraft depend. It is almost always equivalent airspeed that the pilot wants to know.
However the device to measure dynamic pressure, pitot tube, is subject to various errors, so the pilot can't have equivalent airspeed. The best they can get

with simple fixed pitot tube is the Indicated Airspeed, which is affected by changes in angle of attack and side-slip angle (positional error) and also other instrument errors.
with pitot tube attached to an angle of attack vane to keep it aligned with the airflow, and with corrections applied for instrument error, the Calibrated Airspeed, which is the best approximation of EAS that can be provided.

Whatever the instruments provide is the best that can be obtained in given aircraft. There is no way for the pilot to pull out a calculator or E6B and calculate something more precise, and they won't have time for that at the moments it matters anyway. The best the pilot can do is know what magnitude of error can be expected in various flight regimes (which should have been determined in flight testing and listed in the POH/FCOM/QRH) and take it into account.

That doesn't really answer what I'm after. Maybe I need to edit. Are they of some practical use for the pilot? Under what circumstances might a pilot pull out his calculator and compute the EAS or CAS? Are they something normally only used by engineers?

@TomMcW, pilot does not have time to pull out a calculator (or E6B) and calculate anything. And it wouldn't help anyway—the instrument does not correct the error because it does not measure the factors that affect it. Light aircraft rarely have AoA vanes, almost no aircraft have side-slip vanes and the effects of temperature, humidity and such are not usually measured either.

Fantastic answer for explaining what they are. Could do with a simpler/clearer explanation of their usage. How do they relate to true air speed?

@Robert, the question does not mention TAS, so to keep things simple I would prefer not to mention it in the answer either. Feel free to post another question about the relation.

@JanHudec just a thought it might clarify explain it better. TAS is something you hear used more often.

@Robert. nevertheless, TAS is a velocity, unlike EAS and its approximations, IAS and CAS, which are square roots of dynamic pressure. So an altogether different thing.

If TAS is a velocity, why is the direction omitted? A velocity magnitude without a direction is not a vector, but a speed, which is what we call it.

What pilots see in the cockpit of almost all modern aircraft is CAS. Those without an air data computer display IAS. These two will differ only minimally in the number they display in most circumstances.
Pilots use this indicator to try and stay above the minimum flight speed, and below the maximum flight speed specified in the Aircraft Flight Manual. These speed limits are based on aerodynamics - exceed the lower limit and the aircraft will not be able to stay in level flight. (This is an oversimplification!)
The SR-71 Blackbird is one of the very few aircraft that also had an EAS indicator. At very high altitudes this is a more accurate indication than a CAS indicator of where the aircraft speed is in relation to the minimum limit.


text:
Why does the FAA SPL require different endorsements depending on cruise speed?
Part 61 section §61.327 requires that sport pilots require separate endorsements for aircraft with a VH below 87 KCAS and aircraft above 87 KCAS.
What is the reason for two separate endorsements and what is the significance of 87 kn?

Don't know if this has anything to do with it, but 87kn is approx 100mph

For whatever it's worth, most students (that I've spoken to) will just go ahead and get the endorsement for the higher speed during regular training.  Many also get the endorsements for flying in B, C, and D airspace as well.  So, in the end, you get something very close to a PPL, just for smaller planes and no night flying.

When looking at the rules on ecfr.gov you will find references at the bottom of the paragraph indicating the Amendment, Federal Register notices, and other documents related to the rule.
In this case it leads to the following FAA doc.  That document includes the following explanation for the rule;

II.B.5. REQUIRE 1 HOUR OF FLIGHT TRAINING ON THE CONTROL AND
  MANEUVERING OF AN AIRPLANE SOLELY BY REFERENCE TO INSTRUMENTS FOR
  STUDENT PILOTS SEEKING A SPORT PILOT CERTIFICATE TO OPERATE AN
  AIRPLANE WITH A V Current regulations require student pilots seeking a
  sport pilot certificate to receive and log flight training in the
  control and maneuvering of an aircraft solely by reference to flight
  instruments. This training must be received before conducting a solo
  cross-country flight or any flight greater than 25 nautical miles from
  the airport from where the flight originated. It also must be received
  prior to making a solo flight and landing at any location other than
  the airport of origination. These requirements are detailed in § 61.93
  and are applicable to persons seeking a student pilot certificate to
  operate any category and class of aircraft. That section, however,
  does not specify any minimum flight training time to meet these
  requirements. In addition, current regulations for the issuance of a
  sport pilot certificate do not require an applicant to receive flight
  training on the control and maneuvering of any aircraft solely by
  reference to instruments. The FAA is concerned that persons exercising
  student or sport pilot privileges in airplanes with a maximum airspeed
  in level flight with maximum continuous power (VH) greater than 87
  knots calibrated airspeed (CAS) may inadvertently encounter conditions
  less than those specified for VFR operations due to their greater
  speed and range. Operators of these aircraft are more likely to
  encounter instrument meteorological conditions than operators of other
  categories of aircraft. In order to enhance the ability of these
  pilots to appropriately react to the possibility of encountering
  instrument meteorological conditions and the potential consequences of
  attempting continued visual flight rule (VFR) flight in instrument
  meteorological conditions, the FAA is proposing to require persons
  operating an airplane with a VH greater than 87 knots CAS to receive
  and log 1 hour of flight training on the control and maneuvering of an
  aircraft solely by reference to instruments. The FAA recognizes that
  persons may currently be authorized to operate aircraft with a VH
  greater than 87 knots CAS. To provide those persons with a reasonable
  period of time to obtain this training, the agency is proposing that
  the training be completed by 1 year after the effective date of the
  final rule. This training would include straight and level flight,
  climbs and descents, turns to a heading, and recovery from unusual
  flight attitudes. Due to the slower speeds and limited capabilities of
  categories and classes of aircraft other than airplanes, the FAA is
  not proposing that this requirement be extended to operators of those
  categories and classes of aircraft and airplanes with a VH less than
  or equal to 87 knots CAS. The FAA notes that for training to be
  conducted solely by reference to instruments in visual meteorological
  conditions, it must be conducted with a view-limiting device.

My take is that earlier rules covered the conditions with VH less than 87 KCAS.  The FAA felt it was necessary to add rules to cover flight at the higher airspeeds.

If you train in an AC that's >87kn do you also have to train in one <87kn or can you be good for both?

@TomMcW  According to 61.327 the answer is you'll need separate instruction and endorsements to be good for both unless you have logged PIC in a <87 KCAS aircraft before April 2010.  In that case you only need the new endorsement for the >87 KCAS (basically you would be grandfathered for the slower aircraft.)


text:
Can a view limiting device be used in an aircraft requiring two pilots?
Can a pilot use a VLD for IFR currency if the aircraft requires two pilots? Can it be used while carrying passengers? If so, is this ever done?
I'm thinking of part 121 airline pilots under FAA.

I don't see why not, I think the only difference is that the other seat has to be occupied by a pilot rated to be PIC, which is usually done with a training captain. Most commercial passenger flights are flown on IFR flight plans anyway,  even without a VLD. I don't think IFR currency is much of a problem for airline pilots.

@RonBeyer Actually, depending on the types of routes they fly, airline pilots can definitely have problems with currency. Long haul, multi-crew pilots can get very few takeoffs and landings. And, although the flights are all IFR, to count for currency, as I understand it, the approach has to be in actual or simulated IMC

Good point,  I was thinking more of the regional pilots. I don't think using a VLD is a problem though as long as 91.109 is followed, I haven't seen anything in the FARs that seems to say you can't conduct training on revenue flights.

Possibly answered by FAR Appendix F to part 121

There is no regulation against doing so provided that the third person in the cockpit is type rated for PIC privileges on the aircraft and has a waiver from the FAA to operate the aircraft as a single pilot (they are available with some additional training.)  In practice, this would almost never occur both for safety reasons and cost.  In addition full motion simulators are available for most aircraft type rated for a two person flight crew, so it would just be more feasible to carry out the training in one of these using simulated IMC, which is arguably more realistic and accurate than flying the real thing under the hood.


text:
Is the Cirrus Vision SF50 the only civilian monojet currently on production?
Since the Piper PA-47 and Diamond D-jet never made it past prototype stage, is the Cirrus Vision the only single engine civilian turbofan jet in production?
What other monojets have made it into production?

If you include production kits, then there is also the ViperJet MKII and the Sonex SubSonex.

Are you discounting ex-military craft now on the civilian register?

@Simon Yeah. There are quite a few military mono's but I don't hear of many civilian ones.

No there was a prototype PiperJet; it just never made it past that.

"monojet" -- is that like a jet powered monorail?  Or maybe a jet-powered Moni?   ( https://en.wikipedia.org/wiki/Monnett_Moni )  Or maybe a jet that is a monoplane rather than a biplane ( https://en.wikipedia.org/wiki/PZL_M-15_Belphegor ) or triplane (http ???)

He means a single engine jet airplane.  Stop nitpicking

Multiple VLJ kitplanes have been on the market for several decades now; probably the most famous of which was the Bede BD-5J which gained fame in the 007 film Octopussy.  BD-5Js flew in airshows with the Coors Light Silver Bullet aerobatic team.
A supersonic VLJ kit called the Bede BD-10 was planned and flyable prototypes were produced.
And multiple companies have come and gone, offering everything from VLJ kits to wishful thoughts such as the ViperJet to MaverickJets to Stratos.
But near as I know the Cirrus SF-50 is the only certified single engine civilian aircraft for sale today.  Eclipse came close with its E-400, but it only remained a technology demonstrator.
The only other single engine jet airplanes on the market are military.  Aero Vodochody's L-29 and L-39 jet trainers are popular with civilians and air race teams as are MiG-15s -17s, -21s and even a few MiG-23s.  Western fighters like the F-86 Sabre, the Folland Gnat, the De Havilland Vampire, and the BAe Hawk are also popular.

The formerly military jets are not operated as "certified" aircraft. They get restricted experimental airworthiness certificates, usually exhibition-only.


text:
What are the advantages of towbarless pushback tugs?
After watching the video below I wondered the reason for towbarless tugs. Lifting the front wheel of a 575 ton aircraft seems like it requires an awful lot of expensive and complex hydraulics when the goal is just to move the aircraft around on the ramp. What benefit is there to doing this over just using a towbar?

Most of the weight on an aircraft sitting on the ground is supported by the rear wheels. So that video isn't nearly as impressive as it may seem.

Also, when your ultimate goal is to lift that 575-ton aircraft several kilometers into the air, lifting its front wheel a few centimeters doesn't seem like such a big deal. ;-)

It takes a hell of a lot more power to lift it than it does just to move it. At the air show in town my company usually flies in an A300 for a tug-of-war. They attach a rope to the nose gear and 10 people are able to pull it across the ramp. I seriously doubt those same 10 people could lift the nose.

@TomMcW see https://www.youtube.com/watch?v=cHhZwvdRR5c - if the aircraft is mistrimmed, it takes power to keep its front wheel down. Nosewheel carries about 4-10% of the aircraft weight. Those 10 people can speed up the plane and then roll its nosewheel on a 5cm tall ramp - boom, they've just lifted the wheel as the tug did.

@TomMcW - it doesn't take power to lift something, it takes force. With appropriate mechanical advantage, a single person can provide enough force to lift the nose of an airplane. Just as the tug doesn't lift the airplane through direct mechanical connection to the engine (it uses a hydraulic pump (probably) to give it the mechanical advantage that it needs), a person could use a 100 ton bottle jack to get the same mechanical advantage (though there are lots of other ways it could be done.

Lifting heavy thing just a few centimeters is a task surprising unexpensive energetically. Sure, the forces required are high (but hydraulics are great at that) but the since the actual vertical distance travel is small the work involved is afterall pretty low.

Advantages of towbarless pushback.

You don't have to store different tow-bars for different a/c types. This is especially good for ground handlers who handle different airlines with different aircraft types. Also handy for ad-hoc one-off flights.
Removing need for tow-bars means one thing less to check daily, weekly, monthly, annually.
Towing with a tow-bar requires a man in the cockpit to ride the brakes (brake-rider). This also means the aircraft may require power (either from APU or from the towing vehicle) to supply hydraulic pressure. An aircraft towed with a towbar is dependent on the aircraft brakes if a sudden stop is required as the towbar will not be able to take the weight of the aircraft on its own on decelerations.
A normal tug (which uses towbar) needs to be very heavy to enable it to tow an aircraft. Without the weight, the tug will just spin its wheels. The tow--barless tug will have the weight of the aircraft on its wheels so it doesn't need to be as heavy. Just solidly built to support the engine and associated hydraulic stuff. This weight also makes the brakes more effective.
A towbarless can tow the aircraft faster as control is way better. In some busy airports they only allow you to move the aircraft across busy taxiways or during peak hours if it is either taxied under its own power or towed by a towbarless tug. Towing using tow-bar is not allowed as it is very slow.
The tow-bar has 'shear pins' which limit the force which can be applied through the nosewheel towbar points. This reduces the towing speed. They can and do break once in a while. While a spare is usually carried in somewhere on the 'bar it still stakes a few minutes to get in installed. Not fun in the middle of a pushback and may result in a blocked taxiway.
A lot of injuries are caused by towbars. Either they jacknife when something fails or a lapse in procedure caused the nosewheel steering to be activated before the bar has been disconnected. The danger here is the nosewheel is self-centering in almost all aircraft and will swing the bar if the nosewheel is not centered. Scary to see and can take your legs out.

I'm sure there are more aspects but these are the major points. Hope this clarifies a bit.

AKA the real cost is the logistics, not the price. Very true, but often not intuitive.

With a towbar, doesn't someone need to manually attach it and with that lift you can just drive it? Must be faster and nicer in bad weather.

I didn't see this mentioned in Anilv's answer so it may only apply to light aircraft.  In general aviation space, towbarless tugs can also allow for 180 degrees of rotation while keeping the nosewheel straight allowing for greater maneuverability than a towbar alone which is limited by the amount your nosewheel can turn.  I have used one called the AircraftCaddy that does this.  Doesn't add much for a plane with a free-castering nosewheel but definitely aids maneuverability in one with a steerable nosewheel.

That's pretty nifty. Like a pallet jack for your airplane.

I enjoy the contrast between the linked "towbarless tug" and the one in OPs video.

MattD, Commercial airliners have limits as to how much the nosewheel can turn. You often see red stripes or a hatched area on the nose wheel door to indicate the nosewheel should not be turned past that point. While it is possible to disconnect the drag strut (the traingular linkage which connects the top and bottom portions of the nose sear), it is not done as a practise and is usually done to retrieventhe aircraft fro an unnatural parking where a normal tug/towbarless would not get in.

oops.. I see that you meant the towbarless can run 180 degrees while nosewheel is straight. I misunderstood, sorry.

You can see it a little bit in the video linked in my post, couldn't find a good video showing a full 180 degree turn with the nosewheel straight.


text:
What type of unit are flaps settings in?
When the flaps are deployed there are different increments on the control lever. When they are set to, say flaps 10 or 40 what is the number indicating?

The units are degrees. See the dupe in Pondlife's comment for degrees of what angle.

Thanks for the redirect. I did search but did not find that post. The site search does not seem to be all that effective at locating relevant posts.

Yeah, that's unfortunately true. Often Google is better at finding stuff on SE than SE's own search function.


text:
Is it possible to reject a landing after the thrust reversers have been deployed?
Since thrust reversers take time to deploy and stow are you committed to the landing once you engage them?

Related: When a large commercial jet touches down, is it committed to stopping?

No because once thrust reversers are deployed it is nearly possibly and risky to takeoff again. Not enough speed even to takeoff deploying and un deploying the thrust reversers. Especially for big airliners like the 747 or a380(Impossible to get those planes up in the air again after thrust reversers are deployed ) so your answer is no too risky.

I'm not sure this is completely correct.  I'm being somewhat pedantic here, but if you have a long enough runway, there is no reason you could not retract the thrust reversers, increase power, and accelerate back to rotation speed and take off again.  That said, it's extremely unlikely that you'd ever have both enough runway to do this AND the motivation to actually do it under normal commercial operations... .  But that does not mean it's impossible.

@ljwobker Please read the linked question.  The problem is not how much runway remains.  The danger is with asymmetric stowage.


text:
Why is the takeoff decision point based only on speed and not time or distance?
The go/no go decision on takeoff for airliners is calculated as a V1 speed. The question is, why is there no time or distance for V1 calculated. In other words, if we don't reach V1 in X seconds or by X point on the runway the takeoff is rejected.
An example of where this might have prevented disaster is Air Florida Flight 90. The engine inlet probes were frozen, resulting in an inaccurate EPR reading. This caused them to set thrust much lower than they should have. They reached V1 and VR but with degraded lift, due to icing, they were not able to climb over the bridge. The FO felt something was wrong, but the captain told him it was fine and called V1.
The chain of events leading to this accident was very long and full of bad decisions. But had there been a hard and fast rule that if V1 has not been reached by this point then reject takeoff, the chain could have been broken.
Another example of where degraded performance resulted in too long of a takeoff roll is the Lokomotiv YAK-42 crash, although it doesn't appear they even had a V1 speed calculated either. They weren't accelerating fast enough, but the captain carried on expecting it to lift off at any moment. They went right off the end of the runway before it did. The reduced acceleration was obviously not enough to make the captain reject right away and by the time it did become obvious he was out of options.
There may be an unknown number of runway excursions where there was degraded performance and the crew did reject takeoff, but too late to stop.
If an engine has a problem it may continue to function in a reduced capacity then finally failing after V1. The procedures call for continued takeoff after that point, but they may have used up too much runway already.
There are myriad things that can cause degraded performance on a takeoff roll. Anything from tires, brakes, engines to flap configuration, even runway condition can slow you down and it may not be obvious that it's occurring. Many of these things won't show up on an instrument scan or a checklist. It just seems like there's no specific guidance as to how long you wait for V1. How does a pilot know when it's time to call it off?

Look at takeoff performance monitoring systems.

@mins That's pretty much the gist of it, yeah. It's a long question already. Trying to keep it simple

There is a recent Aviation Week article (http://aviationweek.com/business-aviation/gono-go-decision-high-speed-rtos-are-fraught-risk) discussing the danger of RTOs at high speed, and some of the comments on that story make the same observation about the use of only V1.

Some operations, including the USAF, use an acceleration check speed at a given distance (usually 1,000-2,000').  Data is derived from normal acceleration data gathered during performance testing.  The normal acceleration check speed (NACS) check can then be reduced to a Minimum  Acceleration Check Speed (MACS) based on a formula from the aircraft's tech order.
On the GA side, the POH for a multi-engine airplane will include an Accelerate-Stop chart (basically V1 calcs).  The calculated V1 speed will be associated with a runway distance.  This can be (but maybe isn't often) used to check normal acceleration to validate the TOLD Data
Easy answer - takeoff roll/speed checks other than V1 are used, and even V1 has a correlated distance in the takeoff data.

I've never heard of anyone mentioning a specific abort point other than V1 in a briefing. Granted, the only briefings I ever read are from accident cvr's, so maybe they do and I just don't know it.

V1 will be the verbally briefed abort point, especially in Part 135/121 ops.  Military will brief MACS/NACS speed/distance as part of the told brief, depending on local standards.  On the GA side, the POH for the specific airplane will indicate what airspeed was used to reach the calculated Accel/stop distance.  It would likely be found on a redirection line that includes Gross Takeoff Weight

Redirection line? Is that a line drawn diagonally on a graph/chart? Didn't know there was a name for that!

I haven't run across an official name for the lines, but i guess since we are all on the same page, it works!

FWIW, in the Navy we always briefed a Line Speed Check, (NACS/MACS) max abort, (V1) and minimum go, (min speed at which you could accelerate to VR in the runway remaining).  If Max Abort exceeded Min Go there was a no-mans land where you could neither take off, nor abort.   Unless you dropped the tailhook...  We also briefed single engine climb rates - initial, stores emergency jettisoned, and stores off/gear up.


text:
Why is a TFR issued when barometric pressure exceeds 31.00 InHg?
Why does a barometric pressure above 31.00 InHg trigger a TFR?

Because most Kollsman Altimeters cannot be adjusted that high, creating a serious risk to aircrews in less than VFR conditions.  It's also quite an aberration as the usual air pressure range is between 29.5 and 30.50, making erroneous altimeter reading between 500-1000 ft MSL if aircrews forget to adjust the unit.

How often does this happen?

That is because most of the legacy altimeter setting barometers cannot handle such high pressures. Most of them, like the one pictured below has a range from 28 to 31 inches of mercury.

Kollsman Altimeter Setting Indicator, image from analogweather.com
From Aeronautical Information Manual:

7-2-4.  High Barometric Pressure
a. Cold,  dry  air  masses  may  produce  barometric pressures in excess of 31.00 inches of Mercury, and many  altimeters  do  not  have  an  accurate  means of being adjusted for settings of these levels.

As a result, the TFR is triggered by 14 CFR 91.144

(a) Special flight restrictions. When ... barometric pressure on the route of flight currently exceeds or will exceed 31 inches of mercury, no person may operate an aircraft or initiate a flight ...

Is this for all flights, all IFR flights or just in VMC? Seems like it wouldn't be that much of a problem in VMC.

@TomMcW VMC flights use the hemispheric rule to reduce the chances of hitting another airplane. If you can’s set your altimeter, you can’t fly at the appropriate altitude.

An altimeter is also part of the required VFR equipment under 91.205 if it could not operate in the current atmospheric conditions it may be considered in-op and the plane not airworthy for VFR flight.

@JScarry With a little more digging it appears that the TFR just imposes special rules as per NOTAM. AIM 7-2-2 describes what those procedures are. It appears that VFR flights are not restricted but advised to set 31.00 on the altimeter and use extra caution.


text:
How do changes in certification requirements affect previous type certificates?
How does the 2016 part 23 airworthiness requirements rewrite affect older type certificates?

If some aspect of an aircraft does not meet the new requirement do all of those aircraft have to be updated accordingly?
If so, what if the aircraft can't be made to meet new requirements, such as climb rate, etc.
If one of the new rules are less restrictive than the old can those aircraft take advantage of that?
Do newly manufactured aircraft of the same type have to get recertified?
If old type certificates are still valid and the FAA wants one of the new rules to be retroactive will they have to issue airworthiness directives for each type that doesn't meet the new standard?

Old certificates are valid under the rules that they were certified under, they don't have to be recertified or modified in any way, the airframe is grandfathered under the old rules. This is why you can still fly old airplanes without electrical systems.

Sounds like an answer, @RonBeyer. And it makes complete sense, too. I don't think too many Tiger Moths meet current new craft regulations, but I'm sure the FAA would be happy to have one do some flying demonstrations around the country.

@RonBeyer That's true with two caveats. First it is still possible to buy a new plane without an electrical system. It's just that it will be subject to severe operating limitations so there's not a lot of market demand; but they do exist. Second is the changed product rule. If you make a major modification to a certificated aircraft, whatever is modified has to comply with the current rules.

@RonBeyer I was looking at the question on the C208 Caravan. Under the new rules the 14 seat config is still classified as normal category, level 4, low speed. It doesn't reclassify it as a commuter aircraft like the old rules. I wonder how that affects certification of older 208's

@RonBeyer Modern aircraft are still produced without electrical systems.

If you look at the Type Certificate Data Sheet for my 1968 Cherokee, you can see that it was certified under CAR 3. "PA-28-140 and PA-28-151: CAR 3 effective May 15, 1956," To be airworthy, my IA inspects it every year and makes sure it conforms to the TCDS. I can’t make any modifications to it that don’t conform to the original TCDS unless I get a field approval or use an STC.

New rules don't affect t existing designs....
Certification basis is declared by the maker and agreed with the certifying authority...Or authorities... ( ideally it's a common certification basis to avoid extra testing, or building aircraft to  different standards) That basis must reflective rules in existence at the time of application. New or pending  rules may be imposed by Special Conditions or equivaent. Any modifications to that approved design are normally to the same certification basis.
But if a new design comes along, it's the applicable rules at the time of application..
If a change is needed to all aircraft of a certain "class" e.g. Introduction of TCAS, ACAS , then that is imposed by operational requirements, such as Parts 91, 121, 135 etc or their equivalents.


text:
Is there any reason spoilers would deploy just after liftoff?
I was watching this video of a 747-8F taking off.
http://www.dailymotion.com/video/x273atd
Just after liftoff the air brakes and ground spoilers deploy on the left wing causing a sharp roll to the left. You then see the left retract and the right deploy rolling right. Then on the left again to correct.

The second and 3rd deployments on the video are obviously commanded by the pilot to correct for the roll.
Watching several other videos of the 747-8 taking off I don't see any others with spoilers out at any time during takeoff. On 747-8 are the spoilers connected to the ailerons to help with roll? If so, does it take a strong wheel movement to cause this? Why would they have deployed so quickly after takeoff, was this a control input by the pilot? Why would he make such an input?
It looks like they narrowly escaped disaster on this takeoff.

http://www.dailymail.co.uk/travel/travel_news/article-2783901/Captain-dramatically-dips-wings-just-seconds-highly-skilled-stunt.html It's an empty plane on its maiden flight, waving bye bye - no disaster there.

@Sanchises Ah. Intentional maneuver. Nice. Still looks pretty crazy to me. That's a significant roll to be doing at such low speed. The things we do to show off.

Yeah, the Daily Mail called it a "highly skilled manoeuvre", but since it's the Daily Mail, the captain may well have had to explain himself to management for toying with their fresh plane.


text:
Does a flight briefer require a license in the US?
Flight briefers have to stay on top of a lot of different variables. In order to give a pilot the information they need for their flight they must be able to interpret weather forecasts, keep on top of any ATC delays, and wade through all the NOTAM's to find the ones relevant to the flight plan.
The skill set overlaps with those of flight dispatchers. In the US flight dispatchers are required to have a certificate. Are flight briefers required to have a license or certification, either a dispatcher certificate or some other credentials?

Related: AvJobs FSS Job Description. It may be worth noting that in the U.S., weather briefings are provided by a private government contractor, Lockheed Martin.

I imagine that the do receive plenty of training and I belive there was a time where they were "Flight Service Specialists" (this may have changed when LM took over). The FAA offers a great free course through their WINGS program on Flight Briefings and how they work on the other side (from the briefers stand point). I attended it recently and I recall that the woman giving the course was a former briefer and was a Flight Watch Specialist. I don't recall if that was a requirement or not thought (you can always reach out to her and ask). It should be noted that Flight Watch/Lockheed Martin Flight Services are now run by Lockheed Martin on contract to the government and are no longer run solely by the government as they once were, which may have changed things operationally (I have only ever known it in its current state).
As for staying on top of things, in todays modern times that is more the job of a computer than the briefer. Things like NOTAMS and AIRMETS/SIGMETS in route are given to them digitally once you tell them your course/route. There was once a time when this would have been a manual process but those days have long since passed. In my general experience flying VFR on a longer flight the briefer will not give you all the radio outage NOTAMS up front but will ask you if you "want to hear the radio nav aid notams" or something like that. They will give you things with in a certain distance from your planned route or if you ask for it. For example you can say "is VOR XXX in service?" and they will look it up for you.
Other Notes:

There is an interesting discussion on the day to day here.
You can read up on the history here.
And this Article


text:
Why do some airlines have different flight numbers for IATA and ICAO?
Most of the time when I see flights on either flightradar24 or flightaware it doesn't matter whether you use the 2-digit IATA code or the 3-digit ICAO code, the flight number is the same, i.e. a flight will be listed as UA1234/UAL1234.
But some airlines show different flight numbers for IATA and ICAO. Just picking a couple of random flights I can see on Flightradar24:

SunExpress flight XQ231/SXS5J
Pegasus Airlines flight PC398/PGT35R
Turkish Airlines flight TK656/THY3YE

I've also seen this on RyanAir (FR/RYR) flights. Why do the IATA and ICAO identifiers have different flight numbers?


text:
How many warning signals are voiced in modern airliners?
Some warning signal in modern airliners are voiced, like TCAS warning and GPWS warning (PULL UP!).
And how many warning signal are voiced in the modern airliners?
Moreover, where is the sound produced?

A voice warning would have been helpful on Helios flight 522

Modern airliners have voice warnings in a number of systems like,

Ground Proximity Warning System
Terrain Collision Avoidance System
Windshear Alerts
Radio Altitude callouts
Trim
Fire Detection
Autopilot configuration
Pressurization systems
Landing gear system
Stall/overspeed warning.

The amount of voice warnings vary from aircraft to aircraft. For example, airliners.net has the following list of voice warnings in Bombardier CRJ-200 (other than GPWS and TCAS):

"APU" APU overspeed or overtemp
"Door" open or unsafe passenger door indication
"Jetpipe Overheat" overheat indication in jetpipe/pylon
"Smoke" smoke detected in cargo area of lavatory
"Config Autopilot/Flaps/Spoilers/Trim/Brakes" Aircraft not properly
  configured for takeoff
"Wing Overheat" Overheat in fuselage wing anti-ice ducts
"Anti-ice Duct" Bleed air leak in fuselage or wing anti-ice ducts
"Bleed Air Duct" leak in different part of bleed air duct system
"Brakes" brake overheat
"Config Brakes" here again because it's for having the parking brake set
  while airborne
"Gear Disagree" disagreement between gear indications and handle position
"Gear Bay Overheat" overheat in main gear bay
"Nose Door" Nose gear door open after gear fully extended and locked or >250
  knots
"Engine Oil" oil pressure <25 psi

Initially, most of the voice warnings were recorded voices. However, more and more modern systems (like in newer 737s) are using computer generated voices.

Do you have any further reading about the modern computer generated voices for airliners?


text:
How are different parts of airliners handled after the end of life-cycle?
When I was young my father opened a ship equipment shop. He purchased the broken airliners wheel and resell to the ship operators as anti-crash barrier on ship or in the pier like in the picture.

How does the other parts in airliners be used after life cycle?

Recycling! How To Reclaim a Plane and How Do They Do It? - Airplane Recycling. Some military aircraft are exposed in boneyards, I read this is to show them to observation satellites to prove disarmament treaties are actually enforced.

Various parts of the airliners face different fates once it has been decided to breakup the aircraft. Most of the parts are reused in one way or the another. The dismantling of the aircraft starts after removal of hazardous liquids and radioactive components.

Engines- Usually, the aircraft and engines will be at different stages of their lives. The engines are removed and sold for operating in other aircraft. In case the engine life is also considered over, either its components will be used for spare parts or it too will be scrapped for materials.

Source: jalopnik.com

Avionics- The avionics components are usually valuable and are removed for use in other aircraft. Since they are line replaceable units anyway, this should pose no problem.

Stripped down cockpit of 747-400; Image from aviationweek.com

Interior- The interior of the aircraft, like the seats, entertainment systems are stripped and sold off. Items in the galley (like coffee makers), the air-conditioning systems also face the same fate.

Stripped cabin of 747-400; Image from aviationweek.com

Some items like the APU, actuators, landing gear, pipings, etc, if they have life are removed and sold for use in other aircraft (after appropriate checks and certification).
In case the aircraft has removable winglets, they are removed as well, for re-use.
Any hazardous materials like composites, depleted Uranium (used as counterweights in 747s, 727s etc.) are removed and disposed off.
The aircraft (structure) is then cut to pieces and metal parts are melted and reforged for reuse in industries, with unusable parts finding its way to landfill.

Source: tarmacaerosave.aero
The following figure from ICAO report Aircraft End-of-Life: Scrapping and Recycling shows how the materials are reused.

Image from What's new in aircraft materials recycling? ICAO workshop presentation
In general, stripping down and recycling of aircraft involves millions of dollars and is highly efficient, with over 90% reuse of materials being quoted. It remains to bee seen what happens to material reclamation as more and more aircraft components are made from composites.

Ad depleted Uranium: Why did they use Uranium for counterweights?

@DmitriPisarenko: I wondered the same. I would guess it's because uranium is one of the densest materials we can get.

Question is why did they use counterweights at all? According to  http://pbadupws.nrc.gov/docs/ML0321/ML032180089.pdf each 747 had "between 692 and 1059 pounds of DU" in the tail section and there's a handwritten note saying "they thought about it for the wings but chose not to." Seems like unnecessary extra mass. A 747 should be able to fly perfectly well without that mass, and if it were really necessary it should be achievable by redistributing equipment. Ryanair briefly had a policy of closing the first and last few rows of seating to improve aircraft trim, but only for takeoff and landing

Since each aircraft is custom ordered & fitted for the the airline it's sold to, the manufacturer fits ballast to balance the plane based on the customer's specs. I would imagine that there are only so many places the galley can go, and that they can't be moved too much just to balance the entire craft. If you have more 1st/biz class seats, they probably weigh less than economy class, thus something has to be done to balance it out. It's highly unlikely that they'd move fuel tanks, hydraulic pumps/reservoirs/piping, APUs, etc just to balance things out.


text:
Is there any order of loading containers into aircraft instead of weight balance?
Assuming there is some container which have to load into the airliners.
All of them are stored into same size ULD and same weight.
The difference is that some are exclusively passenger luggage, while some are cargo, in which some are more dangerous (eg: more flammable) or less durable.
So, in practice, is there any order of loading those containers into airliners?

Yes, there is.

Premium luggage (business and first class) is loaded such that it is the first to be retrieved.
HAZMAT (HAZardous MATerials and items, if applicable) is loaded differently; and placed in different parts of the cargo hold.

There are some areas of the cargo hold (in passenger airplanes) that cannot be used to store ULD, only loose cargo or other special items (such as the transportation of pets).
Some airlines offer temperature controlled ULDs, which require their own special handling.
Of course, transportation of human remains is handled differently.
Strictly for cargo operations; as these are normally multi-stop trips - the ULDs are loaded in the order in which they are to be unloaded.
However, keep in mind that it is very rare to have perfectly uniformly loaded ULDs or crates. So often the loadmaster has to make sure the CG of the aircraft is taken into account when loading and unloading.